The short version
Pick respond.io if you run a busy B2C team across WhatsApp, Instagram, Messenger, TikTok, email and calls, and you already have a CRM. Pick ActivityTracker if you sell one-to-one from your own number and want the client records and follow-ups in the same app as the chats.
Who should pick which
Stay with respond.io if
- your team handles a lot of chats and calls across several channels
- HubSpot, Salesforce or Zoho is already your system of record
- you want the official WhatsApp API, with Meta's rates and no markup
Pick ActivityTracker if
- you sell one-to-one, and clients message your own WhatsApp number
- you don't have a CRM yet, or it's a spreadsheet
- you want an agent that answers as you and books the meeting on your calendar